The present invention relates to a solenoid control circuit and, more particularly, to a circuit and method for controlling the current flow through a solenoid while simultaneously enhancing the solenoid response time.
Solenoids are used in varying industries and for various applications within these varying industries. For example, in the aerospace industry, solenoids are sometimes used in valves and actuators to move a component. As is generally known, solenoids are constructed using inductive components, which may have a relatively slow response time, from both an activation and a deactivation standpoint. Thus, no matter the particular industry and application, in some instances it may be desirable to speed up the solenoid's response time.
Two methods may be employed to speed up a solenoid's activation time. In particular, there is one way to speed up the activation response time and another way to speed up the deactivation response time. To speed up the activation response time, a relatively high solenoid activation voltage is used. Thus, when the solenoid is activated, this relatively high voltage is applied to the solenoid, which speeds up its activation response time. To speed up the deactivation time, a high power deactivation circuit, such as a low resistance, high power resistor, is used to quickly remove the stored energy from the solenoid.
If a relatively high solenoid activation voltage is used, current levels through the solenoid coil and other circuit components will be substantial. Thus, to keep the current flow to a level that does not damage the circuit components, a current limit circuit may be incorporated. This current limit circuit may be periodically switched on and off, as necessary, to limit the magnitude of the current flow. One drawback of this particular arrangement is that when the current limit circuit is activated, current may flow through the high power deactivation circuitry. Since the current limit circuit may be switched on and off at a relatively high frequency, unnecessary power dissipation may occur. Thus, large and bulky high-power components may be needed, high electromagnetic interference (EMI) emissions may occur, and the overall efficiency of the solenoid driver circuit may be reduced, while the expense and weight of the circuit may be increased.
Hence, there is a need for a solenoid driver circuit that enhances the response time of a solenoid, while addressing one or more of the above-noted drawbacks. Namely, a circuit that does not result in unnecessarily high power dissipation, and/or does not use large and bulky, high power components, and/or does not cause relatively high EMI emissions, and/or has improved efficiency. The present invention addresses one or more of these needs.